Proton Campro 1.6 CFE – The Development Programme.
The
engineering team comprising Proton and Lotus engineers started the design work
at Lotus’ UK Technical Centre outside Norwich, before migration of the project
to the Proton technical center in Shah Alam, Malaysia.
This allowed for
good continuity within the engineering team, as well as building strong
interpersonal links. This method also allowed inexperienced engineers an
unparalleled opportunity to be introduced onto a live project, being mentored by
Lotus and Proton senior engineers. In total, around 30 Proton engineers spent
time at the engineering centre at Lotus.
Web conferencing packages were
used extensively to efficiently communicate between Lotus and Proton, as well as
with vendor engineering teams in Asia and Europe. As well as utilizing Proton’s
existing supply base, many new technology suppliers were used for the CFE
engine. Lotus Engineering Malaysia worked closely with the Proton supplier
quality assurance (SQA) team through the advanced product quality planning
(APQP) process.
Lotus manufacturing engineers worked with Proton
manufacturing engineers to define and plan out the changes needed to the
existing manufacturing facility in terms of equipment and processes to
accommodate the changes of the Campro CFE engine.
Engine dynamometer
testing was carried out at both the Lotus UK and Proton Malaysian test
facilities. Additionally engines and electrically driven rigs were run at vendor
sites to validate key components.
The first prototype engines were
available for test 7 months after kickoff, with the initial design verification
(DV) phase engines built at Lotus using prototype suppliers. Later DV phase
engines would be built offline at Proton using soft tooled parts from production
suppliers, before final process validation engine built on a new final assembly
line in the Shah Alam facility.
The engineering programme included
application of a new torque based engine management system (EMS) as well as the
base engine changes required for the higher performance of the force induction
system’s application. The new system would allow for seamless integration with a
new continuously variable transmission, as well as permitting the vehicle to be
upgraded to the latest levels of electronic stability program
(ESP).
Calibration of the EMS was carried out by Lotus and Proton
engineers, working closely with the transmission supplier (Punch Powertrain) and
also the EMS software and hardware supplier
(Continental SA).
In line
with the product plan, the engine management calibration was proven at low
temperature in Sweden, as well as high temperature/high altitude in Spain and
Malaysia.
Proton Campro 1.6 CFE –
Technical.
Although based on the existing engine family,
retaining many of the key features like bore size, block height, cam positions
etc, the vast majority of the components were replaced or modified in some
way.
One fundamental change was a reduction in stroke from 88 mm to 86
mm. With the retained 76 mm bore, the swept volume reduced from 1,597 cc to
1,561 cc. This was brought about by the very compact height of the existing iron
cylinder block which did not provide enough space to increase the required
piston strength or lower the piston crown to achieve the desired compression
ratio.
The compression ratio was set at 8.9:1, which although relatively
low for a modern downsized engine, allows the same hardware to be used for all
the target markets including those with 88 RON fuel and very hot climates
without excessive retardation.
The cylinder block was based on the
original Campro cast iron block. Extensive finite element analysis (FEA) showed
no requirement to strengthen the casting to withstand the increased cylinder
pressures. Small changes to the block were made to incorporate piston cooling
jets into the oil gallery, and computational fluid dynamics (CFD) driven flow
improvements into the water jacket to improve the engine cooling required for
the performance increase.
A forged steel crankshaft replaced the original
cast iron unit in the engine. FEA indicated that it would be possible to
maintain the existing main bearing and rod bearing dimensions; however it was
necessary to improve the bearing material to withstand the projected
loadings.
A new piston design with a 19 mm floating piston pin to
withstand the higher cylinder pressures was implemented. The cast piston
incorporated an anodised top ring groove to prevent micro-welding damage with
the expected high temperatures, and a scuff resistant coating applied to the
piston skirts.
The changes to the piston and the increased gas pressure
loading necessitated a change in connecting rod and connecting rod length. A new
forged steel fracture cap design replaced the original powder metal
design.
The aluminium 4 valve per cylinder DOHC Campro cylinder head was
re-engineered to accept an intake cam phaser for the CFE application. This was
achieved maintaining the existing cambelt location and now permits 40 crank
degrees of intake cam phasing for improved performance, fuel economy and
emissions. An improved cambelt material was implemented along with an
auto-tensioner for improved serviceability.
During the cylinder head
redesign, the spark plug was changed to a narrow thread, long reach design so
that the spark plug boss would allow better cooling as well as a lower coolant
back pressure in the cylinder head water jacket. In thesame way as the cylinder
block, the water jacket design actions were led by extensive up-front CFD
analysis.Through the reductions in coolant restriction developed through CFD,
only a modest increase in water pump flow rate was required.
A new
multiple layers steel (MLS) cylinder head gasket was developed to withstand the
higher cylinder pressures.
To withstand the expected higher exhaust gas
temperatures, sodium filled exhaust valves maintaining the original 5 mm stem
diameter were selected.
An upgraded oil pump was also implemented to
compensate for the higher demand of piston cooling jets, turbocharger bearing
oil supply, and to maintain good oil pressure at low engine speed so that the
intake variable valve timing (VVT) system could be operated. A water-cooled oil
cooler is fitted as standard.
A Borg Warner turbocharger’s compressor and
turbine were selected for maximum low speed performance. It uses a pressure
regulated wastegate to control plenum pressure, and incorporated an electric
integrated compressor bypass. Air from the compressor is ducted to an air to air
chargecooler mounted in the front left hand side bumper aperture. An electrical
pump which is actuated on key-off to provide coolant to the turbocharger bearing
housing after engine shutdown. This pump also circulates coolant around the rest
of the coolant circuit to prevent boiling, an important feature in the high
ambient temperature of Malaysia and Proton’s export markets.
In line with
the original Campro philosophy, the CFE engine uses a single close-coupled
catalyst as sole exhaust gas after-treatment as a cost effective fast light off
package. Variations in platinum group metals (PGM) loading and substrate density
will cover Euro III to Euro V emissions markets.
The existing two-mode
variable length plastic manifold was replaced with a compact fixed length
plastic manifold for the CFE. The fuel rail was re-engineered to a return-less
design to reduce fuel heating effects, and higher flow fuel injectors fitted to
satisfy the increased performance level.
As well as improvements to
produce and withstand the increased performance, several other changes were made
to reduce the friction of the base engine. These changes included replacing the
original engine’s direct acting hydraulic tappets with lower friction mechanical
graded tappets that are machine selected on the engine assembly
line.
Piston ring heights were reduced allowing lower tangential loads
and the piston skirts now include a low friction coating.
A windage tray
was also added to the oil pan that has been shown to reduce parasitic losses by
up to 1.5 kW. A higher specification lower viscosity mineral oil was specified
to allow extended service intervals along with reduced friction.
